This invention relates to new and improved fluid seal assemblies. The seal assemblies of the present invention are particularly adapted for use as seals for bearings running in an oil bath, and may be installed in the wheel housing of tractors, trailers, semi-trailers, and the like.
Seal assemblies of the invention are provided with an elastomeric sealing element and a casing which provides the primary surface against which the elastomeric element bears to form the primary seal. The assembly of this invention includes, in addition, means which operate to exclude or minimize the ingress of dirt into the assembly to an extent that the effective lubricant action initially established is effectively maintained throughout operation, even under a conditions of an adverse nature.
In preferred embodiments of this invention, a wet or primary seal acts to retain lubricate within the bearing area, and an outer excluder seal and an inner excluder seal act to exclude dirt and other damaging foreign materials from the primary seal area.
Oil seal assemblies of the unitized type are well known and have enjoyed outstanding commercial success. Such oil seal assemblies are highly regarded for their dependability, even under the most adverse operating conditions. However, a finite probability still exists that dirt and other contaminants may penetrate the seal assembly and contaminate the primary seal, leading to eventual failure. When such a failure occurs, related components may be damaged, and contamination of the bearing assembly may also occur.
A failure resulting in leakage can cause brake shoes and/or drums to become oiled, in turn causing erratic stopping control and performance. Brake failure in heavy trucks or other vehicles can create great risks to persons and property. In addition, lubricant leakage can cause dry running and lubricant failure. Eve if the bearings do not run dry, reduced oil levels can cause undesirably increased operating temperatures. Seal failures can therefore cause failure of or damage to adjacent or associated parts of the vehicle.
In most cases, the costs associated with such a failure are much higher than the cost of the oil seal assembly itself. As such, any improvement which reduces the likelihood of failure or shortened life is highly desirable. Seals made in accordance with the present invention provide a substantial improvement over certain heretofore available oil seals of this general type because of a great potential increase in the operating life and other advantages can be achieved.
It is one of the objects of the present invention to provide a new and improved seal assembly having a prolonged operating life.
It is another object of the present invention to provide a new and improved unitized oil bath seal assembly which provides prolonged life for the inner excluder seal and for the primary seal.
It is a further object of the invention to provide an unitized oil bath seal assembly which combines an elastomeric sealing element which is fixed to and in fluid-tight engagement with a first of a pair of movable parts, and a casing element in fixed, fluid-tight engagement with a second of said pair of parts, wherein one element has a sealing surface engaging said elastomeric element, wherein an elastomeric lip is bonded to a portion of one casing element, and in which the sealing element includes an axially extending collar which rotatably engages a portion of an exterior excluder lip body bonded to the casing element.
It is a further object of the invention to provide a unitized oil bath seal assembly which includes first and second casing units, one of which provides a running surface for an elastomeric seal lip and the other of which is bonded to an elastomeric sealing lip and wherein the parts are constructed and arranged so that each of the components includes a generally axially extending collar or like element, with the two collar elements having mutually opposed surfaces in facing relation and molded, cut or otherwise formed to a size such that, upon initial installation, there is sealing contact between the opposed surfaces.
Another object of the invention is to provide a unitized oil bath seal arrangement wherein the elastomeric seal body includes a primary lip portion, an excluder lip portion, and a collar-like element having a circumferentially extending radially outwardly directed area thereof adapted for sealing contact with an opposed circumferentially radially inwardly directed sealing surface on a lip or collar element extending axially outwardly from the casing unit with which the primary and inner excluder lips make sealing contact.
A still further object of the invention is to provide an oil bath type seal for oil hub or like applications wherein two excluder seals are provided, one being a rubber-to-rubber exterior excluder seal and wherein the other is a rubber-to-metal intermediate excluder seal formed between the outer seal and the primary seal.
Another object of the invention is to provide a composite oil bath type seal of unitized construction which may be made at low cost.
Other objects and advantages, and the manner of their attainment will become more clearly apparent from the following detailed description of the preferred embodiments of the invention, and by reference to the drawings, in which like reference numerals indicate corresponding parts throughout.